There’s not much in the way of build details, but judging from this post [dataplex] made several months ago the instrument works on the same principles as an Ebow. There’s a great prototype video showing the hardware and software. One small voice coil reads each string. A tiny op-amp sends this to another voice coil and back into the string. There’s tons of feedback, but it’s great for an ethereal ambiance.

The prototype is controlled by an Arduino via a computer, but for the final build [dataplex] moved on to a copper/zinc touch interface on the front of the harp.

It’s a very, very cool instrument and we’re waiting patiently for the build details to be released. You can check out the videos of [dataplex]’s work after the break.